Add support for Redis Cluster

[dg3feiko]

Redis cluster is a much better solution for HA then sentinel, I tried to pass a cluster enabled redis client to kue.js but it didnt work. I used ioredis as the redis client, its interfaces are very similar to node-redis but with some subtle difference, e.g. message subscription and lua script loading and invocation.

Glad to see redis cluster support in kue.js.
Thanks

[behrad]

Glad too see a PR supporting ioredis according to https://github.com/luin/ioredis/wiki/Migrating-from-node_redis

[tianp]

+1

[behrad]

We should also add support for ioredis. I should check @az7arul's PR.

[VijayKumarMidde]

+1

[verxx]

+1

[chaudhryjunaid]

+1

[chaudhryjunaid]

Although node_redis and ioredis will merge (https://github.com/NodeRedis/node_redis#consolidation-its-time-for-celebration), there seems to be no set timeline regarding this!

[behrad]

Done through #652